WO2024034439A1 - Reflective mask blank for euv lithography, method for manufacturing same, reflective mask for euv lithography, and method for manufacturing same - Google Patents

Abstract

Provided is a reflective mask blank for EUV lithography in which a multilayer reflective film that reflects EUV light and an absorption film that absorbs EUV light are laminated on a substrate in the stated order from the substrate side, wherein the absorption film contains a metal element X as a main component, the crystal structure of the absorption film has a first crystal structure that serves as a stable crystal structure in the bulk state of the metal element X at normal pressure (1 atm) and 25°C and a second crystal structure that is different from the first crystal structure, and the peak area ratio of the second crystal structure is 9% or greater.

Description

Reflective mask blank for EUV lithography and method for manufacturing the same; Reflective mask for EUV lithography and method for manufacturing the same

The present invention relates to a reflective mask blank for EUV lithography used in extreme ultraviolet (EUV) lithography in semiconductor manufacturing, etc., a method for manufacturing the same, and a reflective mask for EUV lithography using the reflective mask blank for EUV lithography. and its manufacturing method.

Conventionally, in the semiconductor industry, photolithography using visible light or ultraviolet light has been used as a technique for transferring fine patterns necessary for forming integrated circuits consisting of fine patterns on Si substrates and the like. However, as the miniaturization of semiconductor devices accelerates, the limits of conventional photolithography methods are approaching. In the case of photolithography, the pattern resolution limit is about 1/2 of the exposure wavelength. Even when using the liquid immersion method, the wavelength is said to be about 1/4 of the exposure wavelength, and even when using the liquid immersion method using an ArF laser (193 nm), the limit is expected to be about 20 nm to 30 nm. Therefore, as an exposure technology for 20 nm to 30 nm and beyond, EUV lithography, which is an exposure technology that uses EUV light with a shorter wavelength than ArF laser, is seen as promising. In this specification, EUV light refers to light rays with wavelengths in the soft X-ray region or vacuum ultraviolet region. Specifically, it refers to a light beam with a wavelength of about 10 nm to 20 nm, particularly about 13.5 nm±0.3 nm.

EUV light is easily absorbed by all materials, and the refractive index of materials is close to 1 at this wavelength. Therefore, a refractive optical system such as the conventional photolithography method using visible light or ultraviolet light cannot be used. For this reason, EUV lithography uses reflective optics, ie, reflective masks and mirrors.

A reflective mask used in EUV lithography has a mask pattern made of an absorbing film that absorbs EUV light on a multilayer reflective film that reflects EUV light with a short wavelength of about 13.5 nm. In order to increase the phase difference between the reflected light from the multilayer reflective film and the reflected light from the absorbing film, it is desirable that the refractive index of the absorbing film is low, and it is also possible to control the reflectance of the absorbing film to an arbitrary value. desirable.

For example, in Patent Document 1, in an absorbing film containing tantalum (Ta) and niobium (Nb), by changing the composition ratio of Ta and Nb, a phase shift mask can be obtained in which the reflectance of the absorbing film has wide selectivity. It is stated that

JP 2021-174003 Publication

However, the absorption film described in Patent Document 1 is an alloy, so the alloy composition ratio needs to be controlled, and the refractive index is relatively high, so it is necessary to form the alloy film with a thickness of about 60 nm. there were.

On the other hand, examples of materials with a low refractive index include ruthenium (Ru), and in order to change the reflectance, it is necessary to use iridium (Ir), etc., which has a larger absorption coefficient for EUV light. is possible. However, if noble metal materials such as Ru and Ir are used as they are, their crystallinity is too high and the LER (line edge roughness), which indicates the roughness of the absorption film pattern, deteriorates, so they are not suitable for reflective masks for EUV lithography. It has been difficult to form the required fine mask pattern.

The present invention has been made in view of these circumstances, and provides a reflective mask for EUV lithography that can reduce the crystallite size of the absorbing film and produce a reflective mask with good LER after patterning of the absorbing film. The present invention aims to provide a type mask blank and a method for manufacturing the same, and a reflective mask for EUV lithography using a reflective mask blank for EUV lithography and a method for manufacturing the same.

As a result of extensive research in order to solve the above problems, the present inventors have determined that the crystal structure of the absorbing film of a reflective mask blank for EUV lithography has been determined in the bulk state of metal element X at normal pressure (1 atm), A crystal structure having a first crystal structure that is stable at 25° C. and a second crystal structure different from the first crystal structure, and the second crystal structure is determined by a peak separation method in an X-ray diffraction (XRD) method. The inventors have discovered that the above problem can be solved by adjusting the peak area ratio of the crystal structure of 9% or more, and have completed the present invention.

That is, the present invention is as follows.
[1] A reflective mask blank for EUV lithography in which a multilayer reflective film that reflects EUV light and an absorption film that absorbs EUV light are laminated in this order from the substrate side on a substrate, the absorption film being , a first crystal structure containing metal element X as a main component, wherein the crystal structure of the absorption film is a crystal structure that is stable at normal pressure (1 atm) and 25° C. in the bulk state of the metal element X; It has a second crystal structure different from the first crystal structure, and has a peak in the range of 30°≦2θ≦55° by a peak separation method in an X-ray diffraction (XRD) method using CuKα rays as a radiation source. The peak area ratio of the second crystal structure calculated when the XRD peak having the top is separated into the first crystal structure and the second crystal structure (peak area of the second crystal structure/ (Peak area of the first crystal structure+peak area of the second crystal structure)) is 9% or more, a reflective mask blank for EUV lithography.
[2] The metal element X is ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), The reflective mask blank for EUV lithography according to [1] above, which is at least one member selected from the group consisting of gold (Au).
[3] The absorption film further includes element Z, and the element Z includes hydrogen (H), boron (B), carbon (C), nitrogen (N), oxygen (O), chromium (Cr), and niobium. (Nb), molybdenum (Mo), hafnium (Hf), tantalum (Ta), and tungsten (W), the EUV lithography according to [1] or [2] above. Reflective mask blank for use.
[4] The absorption film contains Ru as a main component, and has a peak top diffraction angle 2θ of 84° in the range of 75°≦2θ≦90° in an X-ray diffraction (XRD) method using CuKα rays as a radiation source. The reflective mask blank for EUV lithography according to [2] above, which has an angle of 5° or less.
[5] The first crystal structure is one of a face-centered cubic (fcc) structure and a hexagonal close-packed (hcp) structure, and the second crystal structure is one of a face-centered cubic (fcc) structure and a hexagonal close-packed (hcp) structure. The reflective mask blank for EUV lithography according to any one of [1] to [4] above, which has the other close-packed (hcp) structure.
[6] The EUV according to [3] above, wherein the content of the metal element X in the absorption film is 50 atomic% or more, and the content of the element Z in the absorption film is 50 atomic% or less. Reflective mask blank for lithography.
[7] The reflective mask blank for EUV lithography according to any one of [1] to [6] above, wherein the absorption film has a thickness of 60 nm or less.
[8] A protective film for protecting the multilayer reflective film is further provided on the multilayer reflective film, the protective film containing at least one element selected from Ru, Rh, and silicon (Si). The reflective mask blank for EUV lithography according to any one of [1] to [7].
[9] An etching mask film is further provided on the absorption film, and the etching mask film is made of aluminum (Al), Hf, yttrium (Y), Cr, Nb, titanium (Ti), Mo, Ta, and Si. The reflective mask blank for EUV lithography according to any one of [1] to [8] above, comprising at least one member selected from the group consisting of:
[10] The reflective mask blank for EUV lithography according to [9] above, wherein the etching mask film further contains at least one selected from the group consisting of O, N, and B.
[11] A reflective mask for EUV lithography, wherein an opening pattern is formed in the absorption film of the reflective mask blank for EUV lithography according to any one of [1] to [10] above.
[12] A method for manufacturing a reflective mask blank for EUV lithography, comprising forming a multilayer reflective film that reflects EUV light on a substrate, and forming an absorbing film that absorbs EUV light on the multilayer reflective film, the method comprising: The film contains a metal element and a second crystal structure different from the first crystal structure, and the range of 30°≦2θ≦55° is determined by a peak separation method in an X-ray diffraction (XRD) method using CuKα rays as a radiation source. The peak area ratio of the second crystal structure calculated when the XRD peak having the peak top is separated into the first crystal structure and the second crystal structure (the peak area ratio of the second crystal structure) A method for producing a reflective mask blank for EUV lithography, wherein the area/(peak area of the first crystal structure+peak area of the second crystal structure)) is 9% or more.
[13] A reflective mask for EUV lithography, comprising patterning the absorbing film in the reflective mask blank for EUV lithography manufactured by the method for manufacturing a reflective mask blank for EUV lithography according to [12] above to form an opening pattern. manufacturing method.

According to the present invention, there is provided a reflective mask blank for EUV lithography that can produce a reflective mask with good LER after patterning of the absorbing film by reducing the crystallite size of the absorbing film, and a method for manufacturing the EUV A reflective mask for EUV lithography using a reflective mask blank for lithography and a method for manufacturing the same can be provided.

1 is a schematic cross-sectional view showing one embodiment of a reflective mask blank for EUV lithography of the present invention. FIG. 3 is a schematic cross-sectional view showing another embodiment of the reflective mask blank for EUV lithography of the present invention. 1 is a schematic cross-sectional view showing an embodiment of a reflective mask for EUV lithography of the present invention. 3 is a diagram (part 1) showing a procedure for forming a pattern on the reflective mask blank for EUV lithography shown in FIG. 2. FIG. FIG. 3 is a diagram illustrating a procedure for forming a pattern on the EUV lithography reflective mask blank shown in FIG. 2 (part 2). 3 is a diagram showing a procedure for forming a pattern on the reflective mask blank for EUV lithography shown in FIG. 2 (part 3); FIG. 3 is a diagram showing a procedure for forming a pattern on the reflective mask blank for EUV lithography shown in FIG. 2 (Part 4); FIG. It is a crystal lattice image (TEM image) of a sample in an example. It is an electron diffraction pattern of a sample in an example.

Definitions and meanings of terms and notations used in this specification are shown below.
"Containing metal element X as a main component" means "the content of metal element X in the absorption film is 50 atomic % or more." However, the number of metal elements X is not limited to one type, but also includes a plurality of types. Here, when there are multiple types of metal element X, "containing metal element X as a main component" means "the total content of each metal element X in the absorption film is 50 atomic percent or more" It means that. For example, even if the components of the absorption film are 40 at% ruthenium (Ru), 40 at% iridium (Ir), and 20 at% tantalum (Ta), the metal elements X, ruthenium (Ru) and iridium (Ir), Since the total of each content (40 atomic %, 40 atomic %) is 80 atomic %, it corresponds to "contains metal element X as a main component".
The terms "on a substrate, on a layer," and on a film (hereinafter abbreviated as "on a film, etc.") include not only the case where the material is in contact with the upper surface of the film, etc., but also the upper part that is not in contact with the upper surface of the film, etc. For example, "film B on film A" may mean that film A and film B are in contact with each other, or that another film or the like may be interposed between film A and film B. Moreover, "above" here does not necessarily mean a high position in the vertical direction, but indicates a relative positional relationship.
The refractive index is a weighted average value based on the refractive index of each film, taking into account the thickness.
"Sputter etching" is a physical etching process in which ions, neutral particles, etc. generated from etching gas are accelerated by discharge plasma, etc., and collide with the material to be etched, thereby repelling the particles of the material to be etched (sputtering). , and refers to things that are not primarily chemical reactions. On the other hand, "chemical dry etching" is a chemical etching process in which the etching gas causes a chemical reaction on the surface of the material to be etched, producing reaction products with the material to be etched, such as ions, etc. Although it may be accompanied by a sputter assist effect, it is distinguished from physical etching in that it generates a reaction product that is easily volatilized and desorbed by a chemical reaction. The reaction product can be said to be easily volatilized and desorbed if the boiling point is, for example, 400° C. or lower. Note that the boiling point is a value at normal pressure (1 atmosphere).
The thickness of the formed film, etc. is a value measured by an X-ray reflectance method.

[Reflective mask blank for EUV lithography]
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing one embodiment of a reflective mask blank for EUV lithography of the present invention.
A reflective mask blank 1a for EUV lithography shown in FIG. 1 includes a multilayer reflective film 12 that reflects EUV light on a substrate 11, and a protective film that protects the multilayer reflective film 12 from etching when forming a mask pattern. 13 (also called a cap layer) and an absorption film 14 that absorbs EUV light are laminated in this order from the substrate 1 side. However, in the reflective mask blank for EUV lithography according to an embodiment of the present invention, only the substrate 11, the multilayer reflective film 12, and the absorbing film 14 are essential components in the configuration shown in FIG. Any component.
Further, in the reflective mask blank for EUV lithography of the present invention, an antireflection film (not shown) may be formed on the absorption film 14 to facilitate pattern defect inspection after mask processing.
Further, in the reflective mask blank for EUV lithography of the present invention, a buffer layer (not shown) is provided between the protective film 13 and the absorption film 14 to protect the multilayer reflective film 12 during dry etching or defect correction. may be formed.
Furthermore, the reflective mask blank for EUV lithography of the present invention, like the reflective mask blank 1b for EUV lithography in FIG. 2, has a multilayer reflective film 12 that reflects EUV light and a mask pattern formed on the substrate 11. a protective film 13 for protecting the multilayer reflective film 12 from actual etching; an absorbing film 14 for absorbing EUV light; and an etching mask film 15 made of a material resistant to the etching conditions of the absorbing film 14. may be formed in this order.

Hereinafter, individual components of the reflective mask blanks 1a and 1b for EUV lithography will be explained.

(substrate)
The substrate 11 preferably has a low coefficient of thermal expansion at 20°C, preferably 0±0.050×10 ⁻⁷ /°C, more preferably 0±0°C, from the viewpoint of preventing distortion of the transferred pattern due to heat during EUV exposure. 0.030×10 ⁻⁷ /°C, more preferably 0±0.025×10 ⁻⁷ /°C. Further, it is preferable that the substrate 11 has excellent resistance (chemical resistance) to a cleaning liquid used in the manufacturing process of a reflective mask for EUV lithography.
Suitable materials for the substrate 11 include, for example, SiO ₂ -TiO ₂ glass, multicomponent glass ceramics, and the like. Further, as the material of the substrate 11, crystallized glass in which a β-quartz solid solution is precipitated, quartz glass, silicon, metal, etc. can also be used.

The substrate 11 preferably has excellent smoothness from the viewpoint of enabling pattern transfer with high reflectance and high precision, and has a root mean square roughness Rq of preferably 0.15 nm or less, more preferably 0.10 nm. The thickness is preferably 0.05 nm or less.
The substrate 11 has a flatness (TIR; Total Indicated Reading) of preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less, from the viewpoint of enabling pattern transfer with high reflectance and high precision. be.
Note that the root mean square roughness Rq of the substrate 11 can be measured by the method shown in the example.

The substrate 11 preferably has high rigidity from the viewpoint of preventing deformation due to stress of the film laminated thereon, and has a Young's modulus of preferably 50 GPa or more, more preferably 60 GPa or more, and even more preferably is 65 GPa or more.

The size, thickness, etc. of the substrate 11 are appropriately determined based on the design values of the mask, etc. In the example shown later, a SiO ₂ -TiO ₂ glass having an outer diameter of 6 inches (152 mm) square and a thickness of 0.25 inches (6.3 mm) was used.

It is preferable that there be no defects on the surface of the substrate 11 on which the multilayer reflective film 12 is formed. However, even if a defect exists, it is sufficient that no phase defect occurs due to a concave defect and/or a convex defect. Specifically, the depth of concave defects and the height of convex defects on the surface of the substrate 11 on which the multilayer reflective film 12 is formed are preferably 2 nm or less, more preferably 1 nm or less, and still more preferably 0.0 nm or less. 5 nm or less, and the half width of these concave defects and convex defects is preferably 60 nm or less, more preferably 30 nm or less, still more preferably 15 nm or less. The half-width of a concave defect refers to the width at 1/2 the depth of the concave defect. The half-width of a convex defect refers to the width at a position half the height of the convex defect.

(Multilayer reflective film)
From the viewpoint of increasing the reflectance of EUV light, the multilayer reflective film 12 preferably has a structure in which a plurality of layers containing elements having different refractive indexes as main components are periodically laminated. The thickness of each film constituting the multilayer reflective film 12 and the repetition period of lamination are appropriately set according to the film material, desired reflectance of EUV light, and the like. Generally, the multilayer reflective film 12 has a structure in which one period is a set of one high refractive index layer and one low refractive index layer, and about 30 to 60 periods are laminated.
The high refractive index layer/low refractive index layer is generally a Mo/Si multilayer reflective film, but is not limited to this, and includes, for example, a Ru/Si multilayer reflective film, a Mo/Be multilayer reflective film, Mo compound/Si compound multilayer reflective film, Si/Mo/Ru multilayer reflective film, Si/Mo/Ru/Mo multilayer reflective film, Si/Ru/Mo multilayer reflective film, Si/Ru/Mo/Ru multilayer reflective film, etc. Can be mentioned.

The multilayer reflective film 12 preferably has a reflectance of 60% or more, more preferably 62% or more, and still more preferably 65% or more of EUV light having a wavelength of around 13.5 nm and incident light at an incident angle of 6°. Further, even when the protective film 13 is provided on the multilayer reflective film 12, the maximum value of the light reflectance at a wavelength of 13.5 nm is preferably 60% or more, more preferably 62% or more, and still more preferably 65% or more. It is.

The multilayer reflective film 12 can be formed, for example, by forming each constituent film to a desired thickness using a known film forming method such as magnetron sputtering or ion beam sputtering.
For example, when forming a Mo/Si multilayer reflective film by ion beam sputtering, argon (Ar) gas (gas pressure 1.3×10 ⁻² to 2.7×10 ⁻² Pa) is used as the sputtering gas to At an accelerating voltage of 300 to 1500 V and a deposition rate of 0.030 to 0.300 nm/sec, a Si film was first deposited to a thickness of 4.5 nm using a Si target, and then a Mo target was deposited. A Mo film is formed to a thickness of 2.3 nm using the following method. By repeating this as one cycle and stacking the Mo film/Si film for 30 to 60 cycles, a Mo/Si multilayer reflective film can be formed.

(Protective film)
A protective film 13 may be formed on the uppermost surface of the multilayer reflective film 12 . The protective film 13 is provided for the purpose of protecting the multilayer reflective film 12 so that the multilayer reflective film 12 is not damaged by the etching process when a pattern is formed on the absorbing film 14 (described later) using an etching process, usually a dry etching process. It will be done. Therefore, as the material for the protective film, it is preferable to select a material that is less affected by the etching process of the absorption film 14, that is, has a slower etching rate than the absorption film 14, and is less susceptible to damage by this etching process.
The protective film 13 is also provided for the purpose of preventing the multilayer reflective film 12 from being oxidized during EUV exposure and reducing the reflectance of EUV light.

In order to satisfy the above characteristics, the protective film 13 preferably contains at least one element selected from the group consisting of Ru, Pd, Ir, Rh, Pt, zirconium (Zr), Nb, Ta, Ti, and Si. , Ru, Rh, and Si. However, since Ru is also a constituent material of the absorption film 14, when Ru is used as the material of the protective film 13, it is preferable to use an alloy with other elements such as RuZr. Furthermore, the protective film 13 may not only be a single layer but may also be a stack of two or more layers.

When the protective film 13 contains Rh, it may contain only Rh, but it may also contain an Rh compound. In addition to Rh, the Rh compound may contain at least one element selected from the group consisting of Ru, Nb, Mo, Ta, Ir, Pd, Zr, Y, and Ti.

By adding Ru, Nb, Mo, Zr, Y, or Ti to Rh, the extinction coefficient can be reduced while suppressing an increase in the refractive index, and the reflectance for EUV light can be improved. Further, by adding Ru, Ta, Ir, Pd, or Y to Rh, durability against etching gas and sulfuric acid peroxide can be improved. Sulfuric acid peroxide is used for removing resist films, cleaning reflective masks, and the like.

The protective film 13 may further include at least one element selected from the group consisting of O, N, and B. That is, oxides, nitrides, oxynitrides, and borides of the above elements may be used. Specific examples include ZrO ₂ and SiO ₂ .

In the case of an embodiment in which the protective film 13 has two or more laminated layers, at least one layer constituting the protective film 13 may be formed of Rh or a Rh compound. The protective film 13 may have a layer that does not contain Rh.

The thickness of the protective film 13 is preferably 1.5 nm or more and 4.0 nm or less, more preferably 2.0 nm or more and 3.5 nm or less. If the thickness of the protective film 13 is 1.5 nm or more, the etching resistance is good. Moreover, if the thickness of the protective film 13 is 4.0 nm or less, a decrease in reflectance to EUV light can be suppressed.

The density of the protective film 13 is preferably 10.0 g/cm ³ or more and 14.0 g/cm ³ or less. If the density of the protective film 13 is 10.0 g/cm ³ or more, the etching resistance is good. Further, if the density of the protective film 13 is 14.0 g/cm ³ or less, a decrease in reflectance to EUV light can be suppressed.

The root mean square roughness (Rq) of the upper surface of the protective film 13, that is, the surface on which the absorption film 14 of the protective film 13 is formed, is preferably 0.300 nm or less, more preferably 0.150 nm or less. If the root mean square roughness (Rq) is 0.300 nm or less, the absorbing film 14 and the like can be formed smoothly on the protective film 13. Further, scattering of EUV light can be suppressed, and reflectance for EUV light can be improved. The root mean square roughness (Rq) of the upper surface of the protective film 13, that is, the surface of the protective film 13 on which the absorption film 14 is formed, is preferably 0.050 nm or more.

The protective film 13 can be formed using a well-known film forming method such as a magnetron sputtering method or an ion beam sputtering method. For example, when forming a RuZr film using the DC sputtering method, an Ru target and a Zr target are used as the targets, and Ar gas (gas pressure 1.0×10 ⁻² to 1.0×10 ⁰ Pa) is used as the sputtering gas. ) to form a film with a thickness of 2 to 3 nm at a deposition rate of 0.020 to 1.000 nm/sec and a power input to the Ru target and Zr target of 100 W or more and 600 W or less, respectively. .

(absorption membrane)
Examples of the absorption film 14 include a binary film that sufficiently absorbs incident EUV light, and a phase shift film that shifts part of the incident EUV light to a desired phase and reflects it. Among these, from the viewpoint of improving the contrast of the transferred pattern, a phase shift film that shifts a part of the incident EUV light to a desired phase and reflects it is preferable.

The absorption film 14 contains the metal element X as a main component, and the crystal structure of the absorption film 14 is a first crystal structure that is stable at normal pressure (1 atm) and 25° C. in the bulk state of the metal element X. structure, and a second crystal structure different from the first crystal structure.
Here, the first crystal structure is one of a face-centered cubic lattice (fcc) structure and a hexagonal close-packed (hcp) structure, and the second crystal structure is a face-centered cubic (fcc) structure and a hexagonal close-packed structure. Preferably, the other is a packed (hcp) structure.
The crystal structure of the absorption film 14 includes a first crystal structure that is stable in the bulk state of the metal element X at normal pressure (1 atm) and 25° C., and a second crystal structure that is different from the first crystal structure. By having a crystal structure, a first crystal structure that is stable in a bulk crystal and a metastable second crystal structure that is not stable in a bulk crystal coexist.

The peak area ratio of the second crystal structure is not particularly limited as long as it is 9% or more, but from the viewpoint of reducing the crystallinity of the absorption film 14, it is preferably larger, more preferably 12% or more, More preferably, it is 16% or more, particularly preferably 20% or more.
Note that the peak area ratio of the second crystal structure is determined by a peak separation method in an X-ray diffraction (XRD) method using CuKα rays as a radiation source. It is calculated when the peak is separated into the first crystal structure and the second crystal structure, and the peak area of the second crystal structure is calculated by dividing the peak area of the first crystal structure and the second crystal structure. It is obtained by dividing by the sum of the peak area of Note that peak separation based on the above peak separation method is specifically performed by a method shown in Examples described later.
In addition, the type and content of metal element By doing so, the peak area ratio of the second crystal structure can be controlled or adjusted to 9% or more.

There are no particular restrictions on the metal element , Pt, and Au are preferred. Among these, Ru, Rh, Ir, and Pt are more preferred, and Ru, Ir, and Pt are particularly preferred, from the viewpoint of chemical resistance during processing of the absorbent film. Further, from the viewpoint of suppressing reflection from the absorption film and improving the resolution of transfer, a material having a large extinction coefficient k is particularly preferable, and Ir and Pt are particularly preferable. These may be used alone (single element) or in combination of two or more. Here, when two or more types of metal elements are used, the two or more types of metal elements may form an alloy.

When two or more metallic elements The second crystal structure is a metastable crystal structure that is not stable at normal pressure (1 atm) and 25° C. in a bulk state different from the first crystal structure.

There is no particular limit to the content of the metal element The content is at least 60 at%, more preferably at least 60 at%, even more preferably at least 70 at%.

The absorption film 14 in which the metal element hcp) structure, and the second metastable crystal structure which is not stable in the bulk state at normal pressure (1 atm) and 25° C. is the face-centered cubic lattice (fcc) structure. On the other hand, the absorption film 14 in which the metal element The crystal structure is a face-centered cubic lattice (FCC) structure, and the metastable second crystal structure that is not stable in the bulk state at normal pressure (1 atm) and 25° C. is a hexagonal close-packed (HCP) structure.

It is preferable that the absorption film 14 further contains element Z.
Element Z is not particularly limited, but from the viewpoint of reducing the crystallite size, H, B, C, N, O, Cr, Nb, Mo, Hf, Ta, and W are preferable, and H, B, C, N , O, Cr, Hf, Ta, and W are more preferred, H, B, C, N, O, Cr, Ta, and W are even more preferred, and B, C, N, O, Cr, Ta, and W are particularly preferred. These may be used alone (single element) or in combination of two or more.

The content of element Z in the absorption film 14 is not particularly limited, but is preferably 50 atoms in order to have optical properties (refractive index n and extinction coefficient k) suitable for obtaining a desired phase difference. % or less, more preferably 40 atom % or less, still more preferably 30 atom % or less.

When the metal element X is Ru and the element Z is Ta, the ratio of the Ru content (atomic %) to the Ta content (atomic %) (Ru/Ta) is, for example, 30 to 80. If the ratio of Ru content to Ta content (Ru/Ta) is 30 or more, the hydrogen resistance of the absorption film 14 can be improved. If the ratio of Ru content to Ta content (Ru/Ta) is 80 or less, the first selectivity is large and the processability of the absorption film 14 is good. The ratio of Ru content to Ta content (Ru/Ta) is preferably 30 to 80, more preferably 30 to 70, and still more preferably 30 to 60.

When the metal element X is Ru and the element Z is Cr, the ratio (Ru/Cr) of the Ru content (atomic %) to the Cr content (atomic %) is, for example, 1 to 15. If the ratio of Ru content to Cr content (Ru/Cr) is 1 or more, the hydrogen resistance of the absorption film 14 can be improved. If the ratio of Ru content to Cr content (Ru/Cr) is 15 or less, the first selectivity is large and the processability of the absorption film 14 is good. The ratio of Ru content to Cr content (Ru/Cr) is preferably 1 to 15, more preferably 2 to 12, even more preferably 3 to 10, particularly preferably 4 to 8. .

When the metal element X is Ir and the element Z is Ta, the ratio (Ir/Ta) of the Ir content (atomic %) to the Ta content (atomic %) is, for example, 1 to 35. If the ratio of Ir content to Ta content (Ir/Ta) is 1 or more, the hydrogen resistance of the absorption film 14 can be improved. If the ratio of Ir content to Ta content (Ir/Ta) is 35 or less, the first selectivity is large and the processability of the absorption film 14 is good. The ratio of Ir content to Ta content (Ir/Ta) is preferably 1 to 35, more preferably 1 to 30, still more preferably 1 to 20, particularly preferably 1 to 15. , most preferably from 2 to 10.

The thickness of the absorption film 14 is not particularly limited, but from the viewpoint of suppressing shadowing effects (sometimes called projection effects), it is preferably 60 nm or less, more preferably 55 nm or less, and still more preferably 50 nm or less. Moreover, from the viewpoint of obtaining a desired retardation, it is preferably 10 nm or more, more preferably 15 nm or more.

From the viewpoint of reducing crystallinity, when the absorbing film 14 contains Ru as a main component, the absorption film 14 has a peak in the range of 75°≦2θ≦90° in an X-ray diffraction (XRD) method using CuKα rays as a radiation source. The diffraction angle 2θ of the top is preferably 84.5° or less, more preferably 80.0 to 84.0°, and even more preferably 81.0 to 84.0°.

An absorbent film lower layer may be further provided between the absorbent film 14 and the protective film 13. The absorbent film lower layer is a layer formed in contact with the uppermost surface of the protective film 13. By forming the two-layer structure of the absorption film 14 and the lower layer of the absorption film, it is possible to adjust a part of the incident EUV light to a desired phase.

The absorption film 14 can be formed using a well-known film forming method such as a reactive sputtering method, a magnetron sputtering method, or an ion beam sputtering method using the following procedure.

When forming the absorption film 14 using a reactive sputtering method, for example, it contains argon (Ar) gas, O ₂ gas, and N ₂ gas, and the volume ratio of O ₂ is 0 to 30 vol%, N The reactive sputtering method may be performed using a target containing Ru or Ir in an atmosphere where the volume ratio of ₂ is 0 to 50 vol %.

Conditions for the reactive sputtering method other than those mentioned above may be carried out under the following conditions.
Gas pressure: 5×10 ⁻² to 1.0 Pa, preferably 1×10 ⁻¹ to 8×10 ⁻¹ Pa, more preferably 2×10 ⁻¹ to 4×10 ⁻¹ Pa.
Input power density per target area: 1.0 to 15.0 W/cm ² , preferably 3.0 to 12.0 W/cm ² , more preferably 4.0 to 10.0 W/cm ² .
Film forming rate: 0.010 to 1.000 nm/sec, preferably 0.015 to 0.500 nm/sec, more preferably 0.050 to 0.400 nm/sec.

In this specification, the root mean square roughness Rq of the surface of the absorption film 14 measured using an atomic force microscope is used as an index of the smoothness of the surface of the absorption film 14.
In the reflective mask blank 1a for EUV lithography according to an embodiment of the present invention, the root mean square roughness Rq of the surface of the absorption film 14 is preferably 0.50 nm or less, more preferably 0.45 nm or less, and still more preferably 0.50 nm or less. It is 40 nm or less.

Further, the phase difference between the reflected light of EUV light from the multilayer reflective film 12 and the reflected light of EUV light from the absorption film 14 is preferably 150 to 250 degrees, more preferably 180 to 250 degrees, and still more preferably 200 degrees. ~250 degrees.

The use of a reflective mask for halftone EUV lithography is in principle an effective means of improving resolution in EUV lithography. However, the optimal reflectance of a reflective mask for halftone EUV lithography depends on the exposure conditions and the pattern to be transferred, and is difficult to determine unconditionally.

(Anti-reflection film)
An antireflection film (not shown) is preferably laminated on the absorption film 14 to prevent reflection when DUV light (deep ultraviolet light) with a wavelength of 190 to 260 nm is used in the inspection process.
The reflective mask for EUV lithography is inspected for defects in the mask pattern formed on the absorption film 14. In this mask inspection, the presence or absence of defects is determined mainly based on the optical data of the reflected light of the inspection light. Therefore, the light that passes through the mask cannot be used as the inspection light, and DUV light is used. Therefore, for accurate inspection, it is preferable to provide an antireflection film on the absorption film 14 to prevent reflection of DUV light, which is the inspection light.

In order to fulfill the above-mentioned role, the antireflection film is preferably formed of a material that has a lower refractive index for DUV light than the absorption film 14. Examples of the constituent material of the antireflection film include a material containing Ta as a main component and one or more components selected from Hf, Ge, Si, B, N, H, and O in addition to Ta. Specific examples include TaO, TaON, TaONH, TaHfO, TaHfON, TaBSiO, TaBSiON, and the like.

The antireflection film can be formed by forming a film to a desired thickness using, for example, a known film forming method such as magnetron sputtering or ion beam sputtering.

(buffer layer)
The material constituting the buffer layer is not particularly limited, and examples thereof include materials containing SiO ₂ , Cr, Ta, etc. as main components.

(Etching mask film)
It is generally known that a resist film can be made thinner by providing a layer (etching mask film) of a material that is resistant to the etching conditions of the absorbing film on the absorbing film. That is, by forming an etching mask film and lowering the relative speed (etching selectivity) of the etching mask film when the etching speed of the absorbing film is set to 1 under the etching conditions of the absorbing film, the resist The film can be made thinner.

The etching mask film 15 is required to have a sufficiently high etching selectivity under the etching conditions for the absorption film 14.
Therefore, the etching mask film 15 is required to have high etching resistance against dry etching using O ₂ or a mixed gas of O ₂ and halogen gas (chlorine gas, fluorine gas) as the etching gas. .

On the other hand, the etching mask film 15 is preferably removable with a cleaning solution using an acid or a base, which is used as a cleaning solution for a resist film in EUV lithography.

Specific examples of cleaning liquids used for the above purpose include sulfuric acid peroxide (SPM), ammonia peroxide, and hydrofluoric acid. SPM is a solution containing sulfuric acid and hydrogen peroxide, and the sulfuric acid and hydrogen peroxide can be mixed at a volume ratio of preferably 4:1 to 1:3, more preferably 3:1. At this time, the temperature of the SPM is preferably controlled to 100° C. or higher in order to improve the etching rate.

Ammonia peroxide is a mixed solution of ammonia and hydrogen peroxide, and can mix NH ₄ OH, hydrogen peroxide, and water in a volume ratio of preferably 1:1:5 to 3:1:5. . At this time, the temperature of ammonia peroxide is preferably controlled at 70 to 80°C.

In order to meet the above requirements, the etching mask film 15 preferably contains at least one element selected from the group consisting of Al, Hf, Y, Cr, Nb, Ti, Mo, Ta, and Si. Etching mask film 15 may further include at least one element selected from the group consisting of O, N, and B. That is, oxides, oxynitrides, nitrides, and borides of the above elements may be used.

Specific examples of the constituent materials of the etching mask film 15 include Al-based materials such as Al, Al ₂ O ₃ and AlN; Hf-based materials such as Hf and HfO ₂ ; Y-based materials such as Y and Y ₂ O ₃ ; ; Cr-based materials such as Cr, Cr ₂ O ₃ and CrN; Nb-based materials such as Nb, Nb ₂ O ₅ and NbON; Mo-based materials such as Mo, MoO ₃ and MoON; Ta, Ta ₂ O _5, TaON, etc. Ta-based materials; Si-based materials such as Si, SiO ₂ and Si ₃ N ₄ ; and the like.
The etching mask film 15 made of Nb-based material or Mo-based material can be etched by dry etching using chlorine-based gas as an etching gas.
The etching mask film 15 made of a Si-based material can be etched by dry etching using a fluorine-based gas as an etching gas. Note that when a Si-based material is used as the etching mask film 15, removal using hydrofluoric acid as a cleaning solution is preferable.

The thickness of the etching mask film 15 is preferably 20 nm or less in terms of removability with a cleaning solution. The etching mask film 15 made of Nb-based material preferably has a film thickness of 5 to 15 nm.

The etching mask film 15 can be formed by a known film forming method, for example, a magnetron sputtering method or an ion beam sputtering method.

For example, when forming a NbN film by a sputtering method, a gas containing an inert gas (hereinafter simply referred to as an inert gas) containing at least one of He, Ar, Ne, Kr, and Xe and oxygen is used. A reactive sputtering method using an Nb target may be performed in an atmosphere. When using the magnetron sputtering method, specifically, it may be performed under the following film forming conditions.

Sputtering gas: mixed gas of Ar gas and _N2 (volume ratio of _N2 in mixed gas ( _N2 /(Ar+ _N2 ))=15 vol% or more)
Gas pressure: 5.0×10 ⁻² to 1.0 Pa, preferably 1.0×10 ⁻¹ to 8.0×10 ⁻¹ Pa, more preferably 2.0×10 ⁻¹ to 4.0×10 ^-1 Pa
Input power density per target area: 1.0 to 15.0 W/cm ² , preferably 3.0 to 12.0 W/cm ² , more preferably 4.0 to 10.0 W/cm ²
Film formation rate: 0.010 to 1.0 nm/sec, preferably 0.015 to 0.50 nm/sec, more preferably 0.020 to 0.30 nm/sec
Distance between target and substrate: 50 to 500 mm, preferably 100 to 400 mm, more preferably 150 to 300 mm

Note that when an inert gas other than Ar is used, it is preferable that the concentration of the inert gas is in the same concentration range as the Ar gas concentration described above. Moreover, when using multiple types of inert gases, it is preferable that the total concentration of the inert gases is in the same concentration range as the above-mentioned Ar gas concentration.

(Other configurations)
The reflective mask blanks 1a and 1b for EUV lithography of this embodiment may be provided with a known functional film in reflective mask blanks for EUV lithography in addition to the films and layers described above.
For example, in order to adsorb and fix the reflective mask blank 10 for EUV lithography on a mounting portion of an electrostatic chuck, etc., a back conductive film is formed on the surface (back surface) of the substrate 11 opposite to the multilayer reflective film 12. You can leave it there.
The back conductive film preferably has a sheet resistance of 100Ω/□ or less, and a known configuration can be applied. Examples of the constituent material of the back conductive film include Si, TiN, Mo, Cr, TaSi, and the like. The thickness of the back conductive film can be, for example, 10 to 1000 nm.
The back conductive film is formed to a desired thickness using a known film forming method such as magnetron sputtering, ion beam sputtering, chemical vapor deposition (CVD), vacuum evaporation, or electroplating. It can be formed by coating.

[Method for manufacturing reflective mask blank for EUV lithography]
A method for manufacturing a reflective mask blank for EUV lithography according to an embodiment of the present invention includes forming a multilayer reflective film that reflects EUV light on a substrate, and an absorbing film that absorbs EUV light on the formed multilayer reflective film. A method for manufacturing a reflective mask blank for EUV lithography, wherein the absorption film contains a metal element X as a main component, and the crystal structure of the absorption film is in the bulk state of the metal element ), has a first crystal structure as a stable crystal structure at 25 ° C. and a second crystal structure different from the first crystal structure, and the peak area ratio of the second crystal structure is 9% or more. be.
Note that the method for forming the multilayer reflective film and the method for forming the absorbing film are as described above.

[Reflective mask for EUV lithography]
FIG. 3 is a schematic cross-sectional view showing an embodiment of a reflective mask for EUV lithography of the present invention.

In the reflective mask 2 for EUV lithography shown in FIG. 3, a pattern (absorbing film pattern) 140 is formed on the absorbing film 14 of the reflective mask blank 1a for EUV lithography shown in FIG. That is, a multilayer reflective film 12 that reflects EUV light, a protective film 13 of the multilayer reflective film 12, and an absorption film 14 that absorbs EUV light are formed on the substrate 11 in this order, and a pattern is formed on the absorption film 14. (Absorbing film pattern) 140 is formed.

Among the components of the reflective mask 2 for EUV lithography, the substrate 11, multilayer reflective film 12, protective film 13, and absorption film 14 are the same as those of the reflective mask blank 1a for EUV lithography described above.

[Method for manufacturing reflective mask for EUV lithography]
In the method for manufacturing a reflective mask for EUV lithography according to an embodiment of the present invention, the absorption film of the reflective mask blank 1b for EUV lithography manufactured by the method for manufacturing a reflective mask blank for EUV lithography according to an embodiment of the present invention 14 is patterned to form a pattern (absorbing film pattern) 140.

The procedure for forming a pattern on the absorption film 14 of the reflective mask blank 1b for EUV lithography will be explained with reference to the drawings.

As shown in FIG. 4, a resist film 30 is formed on the etching mask film 15 of the reflective mask blank 1b for EUV lithography. Next, as shown in FIG. 5, a resist pattern 300 is formed on the resist film 30 using an electron beam drawing machine.

Next, using the resist film 30 on which the resist pattern 300 is formed as a mask, an etching mask film pattern 150 is formed on the etching mask film 15, as shown in FIG.

Next, using the etching mask film 15 on which the etching mask film pattern 150 is formed as a mask, an absorbing film pattern 140 is formed on the absorbing film 14, as shown in FIG.

Next, by removing the resist film 30 and the etching mask film 15 with a cleaning solution using an acid or a base, the reflective mask 2 for EUV lithography in which the absorption film pattern 140 is exposed is obtained. Although most of the resist pattern 300 and the resist film 30 are removed during the process of forming the absorption film pattern 140, acid or base is used to remove the remaining resist pattern 300, resist film 30, and etching mask film 15. Cleaning is carried out using a cleaning solution.

The reflective mask for EUV lithography of the present invention has a mask pattern formed on the absorption film 14 of the reflective mask blanks 1a and 1b for EUV lithography of this embodiment.
In the method of manufacturing a reflective mask for EUV lithography of the present invention, lithography can be applied, and the etching process is preferably performed as shown in FIGS. 3 to 7 described above. That is, to form a mask pattern on the reflective mask blanks 1a and 1b for EUV lithography, the absorbing film 14 of the reflective mask blanks 1a and 1b for EUV lithography is subjected to a sputter etching process, and then a chemical dry etching process is performed. is preferred.
By manufacturing a reflective mask for EUV lithography by applying such an etching process using the reflective mask blank for EUV lithography of this embodiment, it is possible to form a mask pattern on the reflective mask blank for EUV lithography. It can be done efficiently and accurately.

Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that those skilled in the art can come up with various changes or modifications within the scope of the claims, and these naturally fall within the technical scope of the present invention. Understood. Further, each of the constituent elements in the above embodiments may be arbitrarily combined without departing from the spirit of the invention.

Hereinafter, the present invention will be specifically explained based on Examples, but the present invention is not limited to the following Examples, and various modifications can be made without departing from the gist of the present invention.
Among Examples 1 to 12, Examples 1 to 8 are examples, and Examples 9 to 12 are comparative examples.

[Example 1 to Example 12]
(Production of reflective mask blank for EUV lithography)
A reflective mask blank for EUV lithography including a substrate, a multilayer reflective film, a protective film, and an absorbing film in this order was produced.

As a substrate, a SiO ₂ -TiO ₂ -based glass substrate (outer size: 6 inches (152 mm) square, thickness: 6.3 mm) was prepared. This glass substrate has a thermal expansion coefficient of 0.020×10 ⁻⁷ /°C at 20°C, a Young's modulus of 67 GPa, a Poisson's ratio of 0.17, and a specific stiffness of 3.07×10 ⁷ m. ² / ^s2 . The quality assurance area of the first main surface of the substrate had a root mean square roughness Rq of 0.150 nm or less and a flatness of 100 nm or less by polishing. A Cr film with a thickness of 100 nm was formed on the second main surface of the substrate using a magnetron sputtering method. The sheet resistance of the Cr film was 100Ω/□.
Note that the root mean square roughness Rq of the substrate was measured using an atomic force microscope according to JISB0601:2013.

A Mo/Si multilayer reflective film was formed as the multilayer reflective film. The Mo/Si multilayer reflective film was formed by repeating 40 times of forming a Si film (4.5 nm thick) and a Mo film (2.3 nm thick) using an ion beam sputtering method. The total film thickness of the Mo/Si multilayer reflective film was 272 nm ((4.5 nm+2.3 nm)×40).

As a protective film, a Rh film (single layer, film thickness 2.5 nm) was formed using an ion beam sputtering method.

As the absorption film, a Ru-based absorption film was formed by the method shown in the following "Ru-based absorption film" (Examples 1 to 4 and 9 to 11), and a Ru-based absorption film was formed by the method shown in the following "Ir-based absorption film" (Examples 5 to 8 and 12). ) to form an Ir-based absorption film.

<Ru-based absorption film>
Using a Ru target, a C target, a Ta target, and a _Cr3C2 target, adjust the Ar, _O2 , and _N2 gas flow rates and the power input to each target so that the absorption film composition shown in Table ₁ is obtained by reactive sputtering. Then, absorbent films were formed under the following conditions (1) to (6). A DC power source was used for each target.
(1) Input power: 100-800W
(2) Gas pressure: 0.3Pa
(3) O ₂ gas volume ratio (O ₂ /(Ar+O ₂ +N ₂ )): 0 to 30 vol%
(4) N ₂ gas volume ratio (N ₂ /(Ar+O ₂ +N ₂ )): 0 to 50 vol%
(5) Film deposition rate: 0.050 to 0.400 nm/sec
(6) Film thickness: 35nm

<Ir-based absorption film>
Reactive sputtering was performed using an Ir target, a Ta target, a Ta ₆₀ B ₄₀ target, and a B target. A DC power source was used for sputtering the Ir target, Ta target, and Ta ₆₀ B ₄₀ target, and an RF power source was used for sputtering the B target. The Ir-based absorption film was formed under the same conditions as the Ru-based absorption film.

The elemental compositions (atomic %) of the absorption films of Examples 1 to 12 were measured by X-ray photoelectron spectroscopy (XPS). Note that the composition ratio of Ru and C in Example 3 was measured by energy dispersive X-ray analysis (EDX) because the peaks overlap in XPS and measurement is difficult. In addition, B in Examples 5 to 7 and B and O in Example 8 could not be quantified by XPS because they were outside the detection limit, but it was confirmed that they were contained in the membrane by secondary ion mass spectrometry (SIMS). did. The measured elemental compositions (atomic %) are shown in Table 1.

The thickness of 35 nm for the absorption films of Examples 1 to 12 was measured by an X-ray reflectance (XRR) method.

(Measurement of crystallite size)
The crystallinity of the absorption film was measured using an X-ray diffraction analyzer (MiniFlex II) manufactured by Rigaku Corporation. Crystallite size was calculated using Scherrer's equation for the full width at half maximum of the peak with the highest intensity in the range of 2θ from 30° to 55°. The measured crystallite sizes are shown in Table 1.

(Calculation of peak area ratio, calculation of XRD peak position)
The abundance ratio of each crystal phase was evaluated using the peak area of each crystal phase (first crystal structure, second crystal structure) of the absorption film. Table 1 shows the peak area ratio (%) of the second crystal structure calculated upon peak separation. Note that analysis software "Diffrac.TOPAS" manufactured by Bruker was used for peak separation based on the peak separation method. The profile function was determined by the FP method using the device parameters. A background function was created using a second-order polynomial in the range of 2θ=30 to 75°. Among the diffraction patterns obtained from In-Plane XRD measurement using an X-ray diffraction analyzer (D8DISCOVER) manufactured by Bruker, two fcc structures ((111) plane and (200) plane ), and peaks of three hcp structures ((100) plane, (002) plane, and (101) plane) were used for peak separation. In peak separation, constraint conditions were set so that the crystallite size of each crystal phase did not fall below 1.0 nm.
The XRD peak position of each crystal phase of the absorption film used for peak separation was calculated based on the lattice constant obtained from the analysis of the TEM image described below.

When the main component is Ru, the values of the diffraction angle 2θ at the peak top in the range of 75°≦2θ≦90° in In-Plane XRD measurement using a Bruker X-ray diffraction analyzer (D8DISCOVER) are shown in Table 1. show.

(TEM image measurement)
For the measurement of the TEM image, the thin sample of Example 1 was used, which had been polished from both the absorption film surface side and the substrate side using a focused ion beam method to a thickness of about 50 nm. The sample thin section was observed by TEM using NEOARM manufactured by JEOL Ltd., and a crystal lattice image (TEM image) (FIG. 8) and an electron diffraction pattern (FIG. 9) of the sample were obtained. FIG. 9 also shows simulation results of electron diffraction patterns using the hcp crystal structure of Ru (ICSD No. 76155) and the fcc crystal structure of Ru (ICSD No. 235808) as crystal structure models.
It is thought that the bright and dark areas in Figure 8 each correspond to one crystal grain, and the size of the typical crystal grain indicated by the arrow in Figure 8 is 6 nm. It roughly matched the child size.
The crystal structure of the sample (the first crystal structure , second crystal structure) and their lattice constants were derived.
Note that circle 1, circle 2, circle 3, and circle 4 in FIG. 8 correspond to circle 1, circle 2, circle 3, and circle 4 in FIG. 9, respectively. Circles 1 and 2 indicate portions in which Ru's hcp crystal structure (first crystal structure) is abundant, and circles 3 and 4 indicate portions in which Ru's fcc crystal structure (second crystal structure) is abundant.

As shown in Table 1, in Examples 1 to 8, the peak area ratio of the second crystal structure is 12 to 90%, so the crystallite size of the absorbing film can be reduced, thereby forming a pattern of the absorbing film. It was possible to produce a reflective mask with good subsequent LER.
On the other hand, in Examples 9 to 12, since the peak area ratio of the second crystal structure is 0 to 8%, the crystallite size of the absorbing film cannot be reduced, so that after patterning the absorbing film, It was not possible to produce a reflective mask with good LER.

The reflective mask blank for EUV lithography and the manufacturing method thereof of the present invention, and the reflective mask for EUV lithography using the reflective mask blank for EUV lithography and the manufacturing method thereof of the present invention are suitably used for EUV lithography in semiconductor manufacturing etc. .

1a, 1b: Reflective mask blank for EUV lithography 2: Reflective mask for EUV lithography 11: Substrate 12: Multilayer reflective film 13: Protective film 14: Absorbing film 15: Etching mask film 30: Resist film 140: Absorbing film pattern 150 : Etching mask film pattern 300 : Resist pattern

Claims (13)

1. A reflective mask blank for EUV lithography, in which a multilayer reflective film that reflects EUV light and an absorption film that absorbs EUV light are laminated in this order from the substrate side on a substrate,
   The absorption film contains metal element X as a main component,
   The absorption film has a first crystal structure that is stable in the bulk state of the metal element X at normal pressure (1 atm) and 25° C., and a second crystal structure different from the first crystal structure. It has a crystal structure of
   By a peak separation method in an X-ray diffraction (XRD) method using CuKα radiation as a radiation source, an XRD peak having a peak top in the range of 30°≦2θ≦55° is separated into the first crystal structure and the second crystal structure. The peak area ratio of the second crystal structure calculated when the peaks are separated into the structure (peak area of the second crystal structure/(peak area of the first crystal structure + peak area of the second crystal structure) A reflective mask blank for EUV lithography, having a peak area)) of 9% or more.
2. The metal element The reflective mask blank for EUV lithography according to claim 1, which is at least one selected from the group consisting of:
3. The absorption film further includes element Z,
   The element Z is hydrogen (H), boron (B), carbon (C), nitrogen (N), oxygen (O), chromium (Cr), niobium (Nb), molybdenum (Mo), hafnium (Hf), The reflective mask blank for EUV lithography according to claim 1 or 2, which is at least one member selected from the group consisting of tantalum (Ta) and tungsten (W).
4. The absorption film contains Ru as a main component,
   The EUV lithography according to claim 2, wherein in an X-ray diffraction (XRD) method using CuKα radiation as a radiation source, the diffraction angle 2θ of the peak top in the range of 75°≦2θ≦90° is 84.5° or less. Reflective mask blank for use.
5. The first crystal structure is one of a face-centered cubic (FCC) structure and a hexagonal close-packed (HCP) structure, and the second crystal structure is one of a face-centered cubic (FCC) structure and a hexagonal close-packed structure. The reflective mask blank for EUV lithography according to claim 1 or 2, which has the other (hcp) structure.
6. The content of the metal element X in the absorption film is 50 atomic % or more,
   The reflective mask blank for EUV lithography according to claim 3, wherein the content of the element Z in the absorption film is 50 atomic % or less.
7. The reflective mask blank for EUV lithography according to claim 1 or 2, wherein the absorption film has a thickness of 60 nm or less.
8. Further comprising a protective film for protecting the multilayer reflective film on the multilayer reflective film,
   The reflective mask blank for EUV lithography according to claim 1 or 2, wherein the protective film contains at least one element selected from Ru, Rh, and silicon (Si).
9. An etching mask film is further provided on the absorption film, and the etching mask film is selected from the group consisting of aluminum (Al), Hf, yttrium (Y), Cr, Nb, titanium (Ti), Mo, Ta, and Si. The reflective mask blank for EUV lithography according to claim 1 or 2, comprising at least one selected from the group consisting of at least one selected type.
10. The reflective mask blank for EUV lithography according to claim 9, wherein the etching mask film further includes at least one selected from the group consisting of O, N, and B.
11. A reflective mask for EUV lithography, wherein an opening pattern is formed in the absorption film of the reflective mask blank for EUV lithography according to claim 1 or 2.
12. A multilayer reflective film that reflects EUV light is formed on the substrate,
    A method for producing a reflective mask blank for EUV lithography, comprising forming an absorbing film that absorbs EUV light on the multilayer reflective film,
    The absorption film contains metal element X as a main component,
    The absorption film has a first crystal structure that is stable in the bulk state of the metal element X at normal pressure (1 atm) and 25° C., and a second crystal structure different from the first crystal structure. It has a crystal structure of
    By a peak separation method in an X-ray diffraction (XRD) method using CuKα radiation as a radiation source, an XRD peak having a peak top in the range of 30°≦2θ≦55° is separated into the first crystal structure and the second crystal structure. The peak area ratio of the second crystal structure calculated when the peaks are separated into the structure (peak area of the second crystal structure/(peak area of the first crystal structure + peak area of the second crystal structure) A method for producing a reflective mask blank for EUV lithography, wherein the peak area)) is 9% or more.
13. A method for manufacturing a reflective mask for EUV lithography, comprising patterning an absorbing film in a reflective mask blank for EUV lithography manufactured by the method for manufacturing a reflective mask blank for EUV lithography according to claim 12 to form an opening pattern.

Images